Apparatus for improving the stability of furnaces with magnetically-extended electric arcs.



E. TROYE.

APPARATUS FOR IMPROVING THE STABILITY OF FURNACES WITH MAGNETICALLY I EXTENDED ELECTRIC AR CS I APPLICATION FILED FEE. IS, I9I5- I 1,156,192. Patented Oct. 12, 1915.

To all whom may concern:

UNITED sTA'rEs -P TENT OFFICE,

EINAR TROYE, OF CHRISTIANIA,

KVAELSTOFAKTIESELSKAB, OF CHRISTI! NORWAY, ASSIGNOR T0 NORSK HYDRO-EL JZIKTRISK 1h, NORWAY.

APPARATUS FOR IMPROVING THE STABILITY OF FIiRNACES WITH MAGNETICALLY- EXTENDED ELECTRIC ARCS. I

Specification of Letters Patent.

Patented Oct. 1 2, 1915.

Application filed February 18, 1915. Serial No. 9,062.

lie it known that I, Ihxan Tnorn, a subject of the King of Norway, residing at Christiania, Norway, have invented certain new and useful Improvements in Apparatus for Improving the Stability of Furnaces with Magnetically-Extended Electric Arcs; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains and use the same, reference being had to the accompanying drawings. and toletters or figures of reference marked thereon, which form a part of this specification.

My invention relates to gas reaction fur naces of the Birkeland-Eyde type having magnetically extended arcs, and tl1e. invention has for its object to increase the stability of such furnaces by means of a methodical gas supply for maintaining an increased temperature on the portion adjacent the points of ignition, or foot of the flame. -In furnaces of said type the way in which the gases are supplied to the flame is of great im )ortance, and many different arrangements have been tried with regard to the gas supply. It has been held desirable or even necessary, that cold air or gas should be supplied to the ignition point of the flame, partly for the purpose of accelerating the extension of the flame, and partly to reduce the wear of the electrodes, but more especially to prevent puncture at the central portion of the furnace, where the temperature and the electric tension per linear unit of the arc attain their maximum. From my work with furnaces of the kind referred to I have, however, now found it to be of vital importance that a minimum amount of air should be supplied to the portion adjacent the electrodes and their ignition points, in order to partly maintain the ionization, and also to prevent disturbance of the ignition of the arcs and their displacement along the electrodes by accidental air currents. IVith this arrangement the furnace burns more quietly, is less liable to extinguish, and at the same time works with increased efficiency.

To obtain the above result it is necessary to abandon the uniform perforation of the masonry, and to make use of a restricted perforation over a certain portion around to make the electrodes and their end points. Further, it becomes necessary to prevent as much, as possible the air or gases at these points from participating in the circulation of the furnace The latter object is attained to a certain extent by providing recesses or annular salients, or both in. combination, on a portion adjacent the electrodes. In practice, however, th s would be impracticable, as the pro-existing risk of puncture would thereby be further in- (CltlS0(l, owing to the higher temperature. Secondly, it would not be possible to make perforations at the central portion of the furnace adapted to the conditions of the electrodes, owing to the interference of the furnace magnet,'which extends into the furnace walls at such central portion. A simple withdrawal of themagnets and a corresponding increase in the thickness of' the walls would not make it possible to diminish at the same time the risk of simultaneous rupture and puncture,and would virtually only cause a. disturbance of the magnetic conditions of the furnace. It would be necessary to increase the magnetizing work, and this is not always possible with a furnace of a given 'eonstruction. Therefore, in connection with an elevation of temperature one'must provide against the increased risk of puncture, and ofrupture of the central portion of the furnace without increasing the distance between the poles.

These objects have been attained by my present invention. which also secures a very favorable (liSPOSl'tlOD of the material, as

will be seen from the ,t'ollowing: In order to facilitate the setting of the bricks and the repairs in the furnace, and to secure full control of the air supply, so as to prevent the latter from being hampered by accii'lental openings, fissures and the like, the portion of the wall. through which the air is supplied is generally made in one piece, or in a small number of preferably congruent pieces. lVith a view to the mechanical stability of the masonry, all the parts should be of great thickness. An increased heating of the central portion would cause the fireproof stone to glow and become condifctiv-e, so that the risk of puncture, and of the rupture of the whole central portion of the masonry would be aggravated, owing to the high temperature. I have found, however,

that this risk of rupture owing to the difference of temperature can be avoided by providing a recess in the central portion on the side facing the magnet, and at the same time'the risk of puncture is avoided byallovving an air insulation to be formed between the magnet pole and the most exposed central portion. This also makes it possible should'be left unperforated, toa certain extent may be integral with the thicker portion of the central stone, but I prefer to make it of a more refractory material, such as a special high resistance material, firebricks, steatite, alnminum-oxid, zircon compounds, and the like, which may be set either by means'of mortar or by burning. It will readily be understood that the latter method presents considerable advantage over a central stone made in one piece, as regards security of Working and cost of repairs, and the higher temperatures desirable for the purpose of stability may noW be established Without further proceedings.

In the accompanying draWingsFigures l and 2 show a furnace masonry in section and elevation, provided With arrangements suitable for carrying I out my invention; Figs. 3, 4: and 5, are sectional views of various form of central stones.

at a are the central stones, Which are in serted into a port or aperture in the perforated masonry Z) between the two poles of an ele tro-magnet A, said stones being provided with a recess can extention Z ofWhich runs in the masonry i5 alongthe electrodes Instead of such grooves or recesses, one may also, as shown in Fig. 3, provide ribs e for defining zones of substan or stationary gas. These grooves or recesses may be formed in various Ways. In Fig. 4,

the grooves f and reces. c are both counter-- sunk into the body of. the central stone or tile, while in Fig. 5 the rib 6 projects from the center stone or tile, and the recess 0 is crnintersunk therein. tion may he need, so long as the object of the invention. ts attained, namely to provide means to maintain a. quiescent or substantially quiescent body of air or gas at the electrodes. It will also ben oted that the reaction chamber Within the furnace, Fig. 1, gradually Widens from the central stone a toward, the periphery. By means of inclined perforaz'ions adjacent the central portion one may likewise, to a certain extent, prevent cold air from being blown onto the ignition point of the arcs.

clain1- 1. In an electric arc-disk furnace With .the portions highly infusible silicates,

or gas at the electrodes" ially quiescent Any other constr'ucmagnetically extended fiame, the combination with. the adjacent the foot points of the arc to mamtain a stationary portionof air or gas of comparatively great conductibility adjacent said electrodes to secure a steadily burning arc and enable the electrode distance to be increased.

2. In an electric arc-disk furnace with magnetically extended flame, means consisting of ribs or shoulders partly separating the ignition points of the are from the outer portions of the furnace lining for maintaining adjacent the foot points of the are a stationary portion of air or gas of comparatively great conductibility with the object of securing a steadily burning arc and enabling the electrode distance to be increased.

In an electric arc furnace having a magnetically dispersed arc, the combination with the electrodes of said furnace; of a central furnace portion Whose Walls are thinner than the main portion, and means to maintain a substantially quiescent body of air or gas Within the furnace at such thin- Walled portion.

4. In an electric furnace having a spread arc, the combination. with the electrodes thereof; of a furnace wall adjacen t'the electrodes having a central recess or depression adjacent the electrode points and one or more ribs surrounding said recess 01' depression.

5. In an electric furnace having a magnetically dispersedarc, the combination With the electrodes thereof; of means to produce a'substantially quiescent zone of air and,the furnace Walls at the highly heated zone, this portion of said furnace Walls being much thinner than the remaining portion,- and means to supply air to the outer surface of said thinner, heated Wall portion.

6. Inan electric furnace having a magnetically dispersed arc, the combination with the electrodes, the electrodes a substantially quiescent zone of air or gas Within the furnace chamber, said chamber being narrower at the. electrodes and Widening therefrom. i

7. In an electric furnace having a dispersed are, a furnace chamber formed besaid zone.

8. In an electric furnace having electo the outer faces of the furnace Wall at electrodes thereof; of means of means to produce at zone having of the furnace wall adjacent trodes, an arc dispersing magnet, and a furnace chamber containing the electrodes, a highly refractory thin wall portion for said furnace chamber at the electrodes spaced from the poles of said magnet, and means to produce a zone of substantially quies'cent air or gas at said electrodes, the furnace chamber widening from the electrodes, and means to supply air or gas between the mag- 10 net and the thin Wall portion and thence through dpassages in the furnace Wall beyond sai zone.

In testimony that I claim the foregoing as my invention, I have signed myname in presence of two subscribing witnesses.

. EINAR T ROYE.

l/Vitnessesz M. GoT'roRMsEN, THs. BERG. 

